Luminosity as a function of mass for selected non-rotating (blue) and rapidly rotating models (v_rot,i = 500 km s^-1; red). The labels indicate the initial mass of the considered sequences. The tracks end at a central helium mass fraction of Y_c = 0.98. Overplotted are the mass-luminosity relations of Gräfener et al. (2011) for chemically homogeneous stars with a hydrogen mass fraction of X = 0.74 (labelled ZAMS) and X = 0 (labelled TAMS). The straight line labelled “L ~ M” indicates the smallest expected slope of the mass-luminosity relation.